textproduct: Quad Cities

KEY MESSAGES

- Thunderstorm chances for tonight have diminished to 20-40% with better chances off to the south across Missouri.

- A pattern change this weekend will bring increasing heat and humidity to the area and is forecast to persist through much of next week. The probability of heat indices exceeding 100 degrees continues to increase (70-90% chance) starting Sunday afternoon. An Extreme Heat Watch has been issued for the entire area for Sunday afternoon through Tuesday evening.

SHORT TERM /THROUGH TONIGHT/

Issued at 234 AM CDT Sat Jun 27 2026

The short wave driving the lift keeping light showers and drizzle going acrs the southern third of the DVN CWA overnight will slip off to the east and take this precip activity with it by mid morning. Then western GRT LKS ridging will maintain easterly sfc winds acrs the area today. Despite this, warming thermal profiles support high temps in the lower 80s or even some mid 80s. But expect a lot of the cloud cover to linger today until mid to late afternoon mix out and decrease with upper ridge lobe arrival, and will advertise highs more in the upper 70s to low 80s realm.

A ridge-riding short wave will combine with elevated warm push to try and generate thunderstorms tonight, but several of the latest CAM runs, 00z RRFS, and some deterministics suggest bulk of the activity to occur late night into early Sunday morning mainly to the south acrs MO. Unless we get some secondary elevated showers and storms, lingering inhibiting ridge and building EML may allow just isolated convection in our south or we may get little activity at all into Sunday morning. Will trim POPs southward and downward. Low temps will range from the lower 60s in the northeast, to near 70 in the south. If we have clear skies, some signs of convergent southeasterly sfc flow may allow for at least some patchy fog south of I-80 late tonight.

LONG TERM /SUNDAY THROUGH FRIDAY/

Issued at 234 AM CDT Sat Jun 27 2026

Sunday...the arrival of the warm dome day as the upper ridge is progged to get pressed acrs the mid to upper MS RVR Valley. Fcst soundings continue to show the establishment of a strong EML/cap in the H85-H7 MB layer as the day progresses. This will make it hard for much of any precip to get going, and may just have festering isolated elevated showers trying to go but decay as they drift in acrs the area or try to develop overhead. Of more a story will be the building heat and humidity. Most vertical thermal profiles support highs in the upper 80s to low 90s even with marginal mixing under the inversion. This combined with sfc DPTs climbing into the low to mid 70s(think the NBM widespread mid to upper 70s is overdone even taking into account crop evapo-transpiration) will generate heat index readings in the upper 90s to low 100s. This may be a touch marginal for true heat headlines especially with a breeze increasing on Sunday to 10-20 MPH. But with higher heat on the way and this day being the start of it, went ahead and issued an Extreme Heat Watch for Sunday afternoon through Tuesday evening for now. This taking into account low temps Sunday night and into at least early next week not dropping below the mid to upper5 70s

Monday, Tuesday and Wednesday...A potential true heat wave with ambient highs in the low to mid 90s and sfc DPTs holding up well in the 70s. Long duration heat index period above 100 degrees and consecutive days probably will warrant the eventual issuance of an Extreme Heat Warning through at least Wednesday if not Thursday. Model ensemble of the thermal ridge migration to the east placing the local area closer to the northwest ridge flank ring of fire may allow for some late weak storm chances and rounds of associated debris/cool pools that may interrupt the heat at times by Thursday or Friday, thus much less confidence in the heat sticking all day late next week.

AVIATION /12Z TAFS THROUGH 12Z SUNDAY/

Issued at 633 AM CDT Sat Jun 27 2026

A wide range of flight conditions were seen over the area early this morning, with VFR ceilings along the Highway 20 corridor down to IFR/LIFR ceilings and visibilities over our south. These conditions will persist through the morning hours before gradual improvement by the afternoon, with generally low confidence on the start time of improvement. A warm front will then lift northward through the area late tonight, which could spark some isolated thunderstorms near BRL and help lower ceilings once again area-wide. The trend in the models has been to decrease tonight's storm potential, so have leaned towards a PROB30 group for the storm chances at BRL. Easterly winds will continue throughout the TAF period, sustained around 10 knots.

DVN WATCHES/WARNINGS/ADVISORIES

IA...Extreme Heat Watch from Sunday afternoon through Tuesday evening for IAZ040>042-051>054-063>068-076>078-087>089- 098-099. IL...Extreme Heat Watch from Sunday afternoon through Tuesday evening for ILZ001-002-007-009-015>018-024>026-034-035. MO...Extreme Heat Watch from Sunday afternoon through Tuesday evening for MOZ009-010.